1. Field of the Invention
The present invention relates to a blue color composition containing a dye, a color filter, and a liquid crystal display device and an organic EL display device each including the color filter.
2. Description of the Related Art
A liquid crystal display device has recently come to be valuable for its space saving and light-weight properties thanks to its thin configuration and also for power saving properties. Particularly, these liquid crystal display devices have been rapidly spread in display applications including a television receiver. It is therefore desired that these liquid crystal display devices are more improved in display performances such as brightness, contrast and omnidirectional visibility. It is also desired to develop liquid crystal display devices provided with color filters having higher brightness and higher contrast.
Blue pigments such as C.I. Pigment Blue 15:6, C.I. Pigment Blue 15:3 and C.I. Pigment Violet 23 have been used for the blue filter segment constituting the color filter. These pigments have high heat resistance, light fastness and dispersibility and are therefore frequently used for color filters. However, these pigments are limited in the improvement of transmittance due to their spectral characteristics. These pigments are also limited in the improvement of contrast due to the depolarization specific to these pigments.
In the meantime, it is proposed to use dyes in place of pigments as coloring materials because the dyes have a high transmittance. In this case, triarylmethane-based dyes have the characteristics that they are very distinctive and have high color developing ability and are known as coloring materials for violet and blue colors. However, they have the drawbacks in that they are inferior in robustness including light fastness, heat resistance and hygrothermal resistance.
JP-A 11-223720 discloses a color filter formulated with a metal complex to improve the light fastness of a triarylmethane-based acid dye. However, it has been found by the studies made by the present inventors that this color filter still has unsatisfactory light fastness and hygrothermal resistance. Also, JP-A 2008-304766 discloses a salt of a cationic triaryl compound and Cl− or ArSO3−. However, the present inventors have made studies concerning this color filter and as a result, found that this triarylmethane compound also has unsatisfactory light fastness and hygrothermal resistance.